This invention relates to a process for producing a multilayer structure wherein a film layer of the multilayer structure is adhered to a substrate layer of the multilayer structure, the film of which is particularly suitable for use as a masking, protective, cling or adhesive film for the substrate layer. The film layer applied to the substrate layer may be a monolayer film or a multilayer film.
The use of thin masking films to protect various substrates from scratches, blemishes, oxidation, and the like, is known. However, it is also known that adhering the masking films to the substrates may be difficult. Accordingly, it is desirable to provide a process that will produce a multilayer structure wherein a monolayer or a multilayer film of the multilayer structure is adhered well to a substrate layer of the structure, particularly for use as a masking layer to provide protection for the substrate layer from scratches, blemishes, oxidation, and the like.
The novel process of the present invention for producing the multilayer structures is comprised as follows. A blend comprising an ethylene-alkyl acrylate interpolymer, in an amount of greater than 25 to about 90% by weight, based on the blend, and an ethylene-alpha-olefin interpolymer, in an amount of less than 75 to about 10%, by weight of the blend, is formed into a film by the well-known cast process for producing films. The films from the blends may be produced by the cast process either in the form of a monolayer film, or in the form of a multilayer film with a second layer comprising any polymeric material, such as, for example, a low density polyethylene, a linear low density polyethylene, a high density polyethylene, a polyethylene terephthalate, polyvinyl chloride, polypropylene, ethylene-vinyl acetate, or the like. The resultant cast process produced monolayer film formed from the blend of ethylene-alpha-olefin interpolymer and ethylene-alkyl-acrylate interpolymer, or the cast process produced multilayer film comprising a layer of the film from the blend, is then adhered to a substrate layer by pressing the monolayer film or multilayer film onto the substrate layer. The substrate layer may be any polymeric material, such as polyesters, polycarbonates, acrylics, and the like, or may be glass. It is essential that the substrate layer be maintained at a temperature ranging from about 38 to about 80xc2x0 C. during the pressing of the monolayer or multilayer film onto the substrate layer.
The ethylene-alkyl acrylate interpolymer of the blend comprises from about 70 to about 85% by weight ethylene, based on the interpolymer, and from about 15 to about 30% by weight alkyl acrylate, based on the interpolymer. The ethylene-alkyl acrylate interpolymer has a melt index ranging from about 0.3 to about 20 g/10 minutes. The alkyl acrylate has an alkyl group of from 1 to 10 carbons.
The ethylene-alpha-olefin interpolymer of the blend comprises ethylene and an alpha-olefin having 3 to 16 carbons. The ethylene-alpha-olefin interpolymer has a melt index ranging from about 0.3 to about 10 g/10 min., and a density ranging from about 0.88 to less than 0.920 g/cc.
For the purpose of the present invention, adhesion is regarded as acceptable where a value of 10 to 100 g/inch is measured using the peel test method described herein.